Neurotox Res DOI 10.1007/s12640-015-9518-z
ORIGINAL ARTICLE
Serum Ab is Predictive for Short-Term Neurological Deficits After Acute Ischemic Stroke Yu-Hui Liu • Hong-Yuan Cao • Ye-Ran Wang • Shu-Sheng Jiao • Xian-Le Bu • Fan Zeng • Qing-Hua Wang • Jing Li • Juan Deng • Hua-Dong Zhou • Yan-Jiang Wang
Received: 12 October 2014 / Revised: 29 December 2014 / Accepted: 12 January 2015 Ó Springer Science+Business Media New York 2015
Abstract Mounting evidence suggests that ischemic stroke (IS) is associated with Alzheimer’s disease (AD). IS and vascular risk factors increase the risk for AD. However, whether AD pathologies exist in IS and the effects of these pathologies on stroke remain unknown. In the present study, we aimed to investigate the alterations of serum Ab after acute IS (AIS), and its correlations with the neurological deficits, infarction volume, and site after stroke. AIS patients (n = 35) were recruited within 24 h of symptom onset. Age- and gender-matched AD patients (n = 48) and cognitively normal controls (NC, n = 37) were also enrolled. Serum Ab40 and Ab42 and the National Institute of Health Stroke Scale Score (NIHSS) were measured on day 1, 3, and 7 after stroke onset. We found that serum Ab40 and Ab42 levels were increased at day 1 and reached peak levels at day 3, and decreased to pre-stroke levels at day 7. Serum Ab40 levels at day 1 were correlated with the NIHSS scores and infarction volume of AIS patients. Serum Ab42 levels at day 1 were significantly higher in IS patients with dominant gray matter infarction. Serum Ab40 levels at day 1 were predictive for NIHSS at day 7. Our results indicate that AIS can induce the generation of Ab in the brain, which may in turn be involved in the pathogenesis of neurological deficits after
Yu-Hui Liu and Hong-Yuan Cao have contributed equally to this work. Y.-H. Liu H.-Y. Cao Y.-R. Wang S.-S. Jiao X.-L. Bu F. Zeng Q.-H. Wang J. Li J. Deng H.-D. Zhou Y.-J. Wang (&) Department of Neurology and Centre for Clinical Neuroscience, Daping Hospital and Institute of Field Surgery, Third Military Medical University, 10 Changjiang Branch Road, Yuzhong, Chongqing, China e-mail: [email protected]
stroke. Serum Ab might be predictive for the short-term neurological deficits after AIS. Keywords
Amyloid-beta Ischemic stroke Alzheimer
Introduction Ischemic stroke (IS) is an enormous threat to individual health as a leading cause of death and disability. The association between IS and Alzheimer disease (AD) has been previously reported (Honig et al. 2003; Imfeld et al. 2013). Epidemiological studies have revealed that vascular risk factors increase risk for AD, and cerebrovascular diseases increase the incidence and aggravate the clinical symptoms of AD (Breteler et al. 1994; Helzner et al. 2009). However, the pathophysiological mechanism underlying these associations remains unknown. Amyloid-beta peptide (Ab) is suggested to play a pivotal or causative role in the pathogenesis of AD. Overproduction or accumulation of Ab in the brain can cause secondary pathological events such as hyperphosphorylation of tau, neuroinflammation, oxidative stress, neurite degeneration, and neuronal death, which subsequently lead to dementia (Hardy and Selkoe 2002). The association between cerebral Ab and brain ischemia has been previously reported (Aho et al. 2006; Jendroska et al. 1995; Nihashi et al. 2001; PopaWagner et al. 1998). Previous studies have demonstrated that ischemic attack is associated with transient Ab accumulation in the brain of animals (Garcia-Alloza et al. 2011), and serum of after acute IS (AIS) patients (van Dijk et al. 2004). This might be resulted from increase in Ab generation via enhanced b- and c-cleavage of amyloid-beta peptide precursor (APP) (Li et al. 2009), or impaired cerebral Ab clearance after ischemic attack (Weller et al. 2002).
123
Neurotox Res
However, while we are thinking that IS contributes to the pathogenesis of AD, it remains unknown the impact of elevated Ab on the functional outcomes of AIS. As brain Ab equilibrates with serum Ab, serum Ab can reflect the levels of brain Ab (Roberts et al. 2014). In the present study, we investigated the alterations of serum Ab levels after AIS, and the correlations between serum Ab and the neurological deficits after stroke.
Subjects and Methods Subjects A total of 35 AIS patients, who were not suitable for thrombolysis due to their onset-to-door time was more than 4.5 h, were consecutively recruited from Daping Hospital during December 2013 to May 2014. Thirty seven age- and gender-matched cognitively normal controls (NC) were randomly recruited from health examination center of Daping hospital at the same time frame. Forty eight age- and gender-matched AD patients were randomly selected from bank of Chongqing Aging Study (Li et al. 2011). The subjects were not eligible if they: (1) had a history of dementia or mild cognitive impairment before stroke; (2) had severe cardiac, pulmonary, hepatic, renal diseases, or any kinds of tumors; (3) had chronic autoimmune or inflammatory diseases, or were on long-term use of nonsteroidal antiinflammatory drug; and (4) declined to participate the study. The study was approved by the Institutional Review Board of Daping Hospital, and registered in the Chinese Clinical Trial Registry (No. ChiCTR-OCC-12001966). Clinical Assessment and Treatment of AIS Patients The demographic data, medical history, and severity of neurological deficits were collected and assessed. All patients underwent computed tomography (CT) of the head at admission, and underwent angiography (CTA) and magnetic resonance imaging (MRI) of the head 24 h later after disease onset. Diagnosis of AIS was made based on the persistent symptom and signs of neurological deficits and acute ischemic lesions on brain imaging. Fasting blood was sampled for measuring hemogram, fasting glucose, thyroxin, creatinine, uric acid, transaminase, total cholesterol, Ab40, and Ab42. Blood was sampled between 07:00 and 09:00 a.m. in order to take into account a possible circadian rhythm; serum was separated within 30 min after sampling and stored at -80 °C until further analysis. For the recruited AIS patients, blood was sampled at the 1st, 3rd, and 7th day after stroke onset. Meanwhile, the severity of AIS was evaluated with the National Institutes of Health Stroke Scale (NIHSS, a 15-item validated neurological
123
examination scale with scores ranging from 0 to 42, with higher scores indicating greater deficits) at admission, day 3, and 7 after stroke onset. AIS patients were treated with standard medical care in a dedicated stroke unit. No AIS patients included in the study were treated with thrombolysis during their hospital stay. Magnetic Resonance Imaging (MRI) All MRI were performed on a 3.0 Tesla clinical whole-body scanner with echoplanar capabilities. The MRI protocol included a T1- and a T2-weighted sequences, a fluid-attenuated inversion recovery sequence and an axial diffusion weighted imaging (DWI) sequence as described previously (Kruetzelmann et al. 2011). DWI infarction volumes were calculated using locally established software. The infarction sites of each patient were evaluated by radiologists. Measurement of Serum Ab Serum Ab40 and Ab42 levels were measured using commercial ELISA kits (Betamark, Covance) according to the manufacturer’s instructions. Samples and standards were measured in duplicate, and the means of the duplicates were used for statistical analyses. Investigators were blinded for information of samples. Statistical Analysis All statistical analyses were performed with the software SPSS 18.0. The data were expressed as the mean ± SD, and significance was achieved when p \ 0.05. Continuous variables were tested for normal distribution with the Kolmogorov–Smirnov test. Differences in variables among groups were assessed using analysis of variance, Kruskal–Wallis tests, and Chi square tests, where appropriate. Paired samples t tests were used for the comparison of serum Ab levels at two different time points. The correlations between serum Ab levels and NIHSS scores of AIS patients were tested using Spearman correlation analysis. Linear regression models were used to test the role of serum Ab levels at the 1st day after the stroke onset in predicting the NIHSS scores at the 7th day when the discharge was planned for most of the patients.
Results Demographic Characteristics of Study Subjects The detailed demographic characteristics of subjects in the study are shown in Table 1. In the subjects of present study, there was no significant difference in characteristics of age, gender, education, frequencies of hypercholesterolemia, and
Neurotox Res Table 1 Demographic characteristics of study subjects NC (n = 37)
AD (n = 48)
Stroke (n = 35)
p
Female (%)
18 (48.65)
27 (56.25)
Agea
64.19 (42–71)
64.65 (49–77)
Educationb
9 (0–16)
9 (0–16)
Hyperlipidemia (%)
3 (8.11)
4 (8.33)
Hypertension (%)
10 (27.03)
10 (20.83)
19 (54.29)
0.004
DM (%)
3 (8.11)
8 (16.67)
6 (17.14)
0.445
Day 1: NIHSSc
NA
NA
7 (1–18)
NA
Day 3: NIHSSc
NA
NA
3 (0–13)
NA
Day 7: NIHSSc
NA
NA
2 (0–10)
NA
Infarction volume
NA
NA
Time intervaleIS
NA
NA
d
12 (34.29)
0.139
63.40 (42–89)
0.943
9 (0–16)
0.335
3 (8.57)
0.997
1.66 (0.10–102.35)
NA
9 (4–12)
NA
Time intervalIS between stroke onset and blood sampling NA not applicable, NIHSS National Institute of Health Stroke Scale Score a
Mean age in years (range)
b
Median education in years (range)
c
Median score (range)
d
Median volume in ml (range)
e
Median time intervalIS in hours (range)
diabetes mellitus (DM) among groups. AIS patients had higher frequencies of hypertension than AD patients and NC. Representative MRI images of all AIS patients are shown in Fig. 1.
Changes of Serum Ab Levels After Stroke Firstly, we compared serum Ab levels of the AIS patients with that of AD patients and NC. Serum Ab40 and Ab42 levels of AIS patients at day 1 (Ab40, p \ 0.001; Ab42, p = 0.014) and day 3 (Ab40, p \ 0.001; Ab42, p = 0.007) were significantly higher than that of NC. Notably, serum Ab40 (p = 0.032) and Ab42 (p = 0.034) levels of IS patients at day 3 were significantly higher than that of AD patients. Serum Ab40 (p = 0.366) and Ab42 (p = 0.204) of IS patients at day 7 decreased to pre-stroke levels. We next investigated the time course of changes in serum Ab levels after AIS. Interestingly, serum Ab40 reached a peak levels at day 3 (day 1 vs. 3, p = 0.039), and decreased to the levels which were comparable with that of NC at day 7 (day 3 vs. 7, p \ 0.001). However, there was no significant increase in serum Ab42 levels at day 3 relative to day 1 (p = 0.639). Similar to serum Ab40 levels, serum Ab42 levels decreased at day 7 (day 3 vs. 7, p = 0.018) (Fig. 2). Serum Ab40 (p = 0.372) and Ab42 (p = 0.204) levels of AIS patients at day 7 were comparable with that of NC. These data suggest that serum Ab levels increased at day 1 and 3, and decreased to normal levels at day 7 after onset of stroke.
Correlations Between Serum Ab Levels and NIHSS Scores After Stroke We then investigate the correlations between serum Ab levels and the severity of neurological deficits in AIS patients. Serum Ab40 levels at day 1 were correlated with the NIHSS scores at day 1. However, serum Ab40 levels at day 3 and 7 were not correlated with the NIHSS scores at the corresponding days. Meanwhile, serum Ab42 levels were not correlated with NIHSS scores at the corresponding days (Table 2). We further conducted linear regression analysis to investigate the role of serum Ab levels at day 1 for predicting NIHSS scores at day 7 when most of the AIS patients were planed for discharge, with NIHSS scores at day 7 as dependent variable and the contributing factors, including age, gender, education, hyperlipidemia, hypertension DM, and the time interval between stroke onset and blood sampling as independent variables. Interestingly, we found a significant predictive effect of serum Ab40, but not Ab42 levels, at day 1 for NIHSS scores at day 7 (Table 3). Correlations of Serum Ab Levels with Infarction Volume and Site of Stroke Spearman correlation analysis was conducted to investigate the correlations between serum Ab levels and lesion volumes of AIS patients. Interestingly, serum Ab40 levels at day 1 were correlated with infarction volume of AIS.
123
Neurotox Res
Fig. 1 Representative MRI images of all the AIS patients in the study. Infarction lesions are demonstrated as hyperintensive signals in DWI. The numbers at upper left of each image denote the patient number
However, no correlations were observed between serum Ab42 levels and infarction volume (Table 2). Then, we investigated the correlation between serum Ab levels and infarction sites. AIS patients were divided into gray matter dominant (GMD) group (n = 22) in which the infarction zone is mainly composed of gray matter and the white matter dominant (WMD) group (n = 13) in which the infarction zone is mainly composed of white matter. Serum Ab40 levels were not significantly different between the two groups. Serum Ab42 levels at day 1, but not day 3 and 7, were significantly higher in the GMD group in comparison with that in the WMD group (Fig. 3).
Discussion In the present study, we found that serum Ab40 and Ab42 levels were increased after AIS. Serum Ab40 and Ab42
123
reached peak levels at day 3, and returned to levels which were comparable with normal levels at day 7 after AIS onset. Serum Ab40 levels were correlated with the infarction volume, and serum Ab40 levels at day 1 were predictive for the NIHSS scores at day 7. Serum Ab42 levels at day 1 were significantly higher in AIS patients with GMD infarction relative to those with WMD infarction. As common morbidities and leading causes of death and disabilities among the elderly (Ballard and O’Sullivan 2013), AD and IS are mutual risk factors for each other (Chi et al. 2013; Honig et al. 2003) and share common risk factors such as age, smoking (Deng et al. 2010), and apolipoprotein E status (Fekih-Mrissa et al. 2014). Cognitive functions essentially depend on cerebrovascular health and cognitive decline frequently occurs after IS (Muresanu et al. 2014). In AD patients, dysfunction of cerebral autoregulation and structural deterioration in cerebral blood
Neurotox Res
Fig. 2 Serum Ab levels are increased and change over time in AIS patients. Serum a Ab40 and b Ab42 levels in normal NC, AD patients and AIS patients at day 1, day 3 and day 7, Asterisk compared with
Table 2 Correlations between serum Ab levels and NIHSS scores of AIS patients
Ab
Time
NC, hash compared with AD. Changes of serum c Ab40 and d Ab42 levels along with time. * and #p \ 0.05, ** and ##p \ 0.01
NIHSS
Infarction volume
Day 1 c Ab40
Ab42
Day 3 c
p
Day 7 c
p
c
p
p
Day 1
0.350
0.039
0.251
0.147
0.306
0.074
0.441
Day 3
-0.207
0.234
-0.285
0.097
-0.190
0.274
0.322
0.008 0.059
Day 7
-0.155
0.374
-0.169
0.332
0.000
0.996
-0.230
0.183
Day 1
-0.003
0.986
-0.024
0.889
-0.139
0.426
0.039
0.826
Day 3
-0.038
0.829
-0.099
0.573
-0.244
0.157
0.217
0.211
Day 7
0.259
0.132
0.111
0.526
0.137
0.433
0.173
0.321
Table 3 Predictive effects of serum Ab levels at day 1 for NIHSS scores at day 7 after onset of AIS using linear regression models Variable
Coefficient
SE
t
p
95 % confidence interval
Ab40
0.044
0.018
2.503
0.019
0.008–0.081
Ab42
-0.013
0.018
-0.696
0.493
-0.049–0.024
Adjusted for confounders, including age, gender, education, hyperlipidemia, hypertension, DM, and the time interval between stroke onset and blood sampling
123
Neurotox Res
Fig. 3 Comparison of serum Ab levels according to infarction site. *p \ 0.05, **p \ 0.01. GMD denotes gray matter dominant group and WMD denotes white matter dominant group
vessels impairs the cerebral blood flow and increases the neuronal degeneration and susceptibility to ischemia (Popa-Wagner et al. 2013). IS is revealed to increase the risk for AD, especially in cases with vascular risk factors such as hypertension, diabetes, or heart diseases (Honig et al. 2003). In our and others’ studies, vascular risk factors are suggested to promote AD incidence (Li et al. 2011) and progression (Helzner et al. 2009; Li et al. 2010). AD also increases the risk for cerebrovascular events, such as IS (Chi et al. 2013) and hemorrhage (van Duinen et al. 1987), which is likely due to Ab-directed vascular impairment (Nakata-Kudo et al. 2006). Previous animal studies suggest that ischemia lesions may lead to rapid deposition of Ab in the brain (GarciaAlloza et al. 2011). This was consistent with a previous human study which indicates that IS stress induces deposition of Ab immunoreactivity in the brain (Jendroska et al. 1995). It is further demonstrated that IS is associated with focal Ab deposition at the ischemic sites (Ly et al. 2012). The local ischemic effect on Ab accumulation in IS brain may be related to an upregulation and alteration of APP processing favoring amyloidogenic pathways, with increased b-secretase activity observed in rats after transient ischemic attack (Wen et al. 2004). Likewise, as ischemia is always accompanied with neuroinflammation, it is suggested that neuroinflammation also plays a role in promoting Ab generation and accumulation after stroke (Thiel et al. 2014). It is also possible that Ab clearance abilities were compromised after AIS (Garcia-Alloza et al. 2011). As there is equilibrium of Ab between the periphery and the brain, Ab might efflux from brain to periphery after ischemic insult (Lemere et al. 2003). Accordingly, levels of serum Ab can reflect the Ab levels in the brain. Human evidence regarding serum Ab levels after AIS is still lacking. In the present study, we found that AIS patients
123
had increase in both serum Ab40 and Ab42 levels, which are consistent with a previous study demonstrating increased peripheral Ab40 levels after AIS (van Dijk et al. 2004). The increase of Ab species in periphery might be subsequent to the increase of Ab in the brain after ischemic attack and its efflux into periphery. Another possibility is that brain ischemic insults may increase the permeability of the blood–brain barrier (Fernandez-Lopez et al. 2012). The two mechanisms may work synergistically. It is notable that serum Ab levels were increased at the first day after stroke onset, indicating that the increase of serum Ab might be an acute phase response to AIS. Interestingly, we further found peak levels of serum Ab at day 3 and normal levels at day 7, indicating that the increase of Ab after AIS is transient. This is consistent with previous animal studies (Garcia-Alloza et al. 2011), and can explain the paradox that there is no local increase in amyloid burden adjacent to cerebral infarcts in human brain (Garcia-Alloza et al. 2011). Although previous animal studies had revealed the Abinduced susceptibility to brain ischemia damage (Zhang et al. 1997), an important issue regarding whether the transient increase of Ab had an impact on neurological deficits after stroke still remains unclear. In animal models, Ab is suggested to be involved in stroke-related pain and allodynia (Lorenz et al. 1998; Takami et al. 2011) and cognitive impairment after stroke (Thiel et al. 2014). Brain injection of Ab results in hippocampal atrophy, AD-like pathologies, and cognitive deficit in animal models of stroke (Amtul et al. 2014). In the present study, we found that Ab levels were correlated with neurological deficits after AIS, suggesting that Ab is an important factor involved in the pathogenesis of stroke. Previous studies suggest that increase of Ab is confined focally around the ischemic site (Ly et al. 2012). This might explain the correlations between serum Ab40 levels at day 1 with infarction volume of AIS patients in the present study (Table 2). Moreover, we found that serum Ab42 levels at day 1 were significantly higher in the GMD group relative to WMD group. Serum Ab40 levels at day 1 and Ab42 levels at day 3 were slightly higher in the GMD group, although no statistical significance was reached. This finding suggests that neurons under ischemia might be more prone to generate Ab compared with ischemia of axons. Another important finding in the present study is that serum Ab40 levels at the onset day of AIS predict the NIHSS scores 1 week after, suggesting that Ab is involved in the pathogenesis of neurological deficits after AIS, and Ab might be a biomarker of severity of AIS. Compared with Ab40, Ab42 may be less prone to efflux from the brain to blood, as it has higher capacity of aggregation and is prone to deposit in the brain (Kim and Hecht 2005). Thus, serum Ab42 might be less sensitive to reflect brain
Neurotox Res
pathogenesis of ischemia than Ab40, as demonstrated in the present study. In summary, the present study is the first study to investigate the alterations of serum Ab levels in IS patients with the disease progression. Our findings suggest that AIS can induce transient generation of Ab in the brain, which might in turn be involved in the pathogenesis of neurological deficits after AIS. Serum Ab is predictive for the neurological deficits after stroke, suggesting that Ab is involved in the development of neurological deficits after stroke. The pathophysiological significance of the shortterm increase of serum Ab for long-term prognosis of the disease needs to be addressed in the future. Acknowledgments This work was supported by the National Natural Science Foundation of China (30973144), PLA Healthcare Research Grant (13BJZ31), Chinese Postdoctor Scientific Grant (2013T60955), and Chongqing Postdoctor Research Grant (XM201342). Conflict of interest
None.
References Aho L, Jolkkonen J, Alafuzoff I (2006) Beta-amyloid aggregation in human brains with cerebrovascular lesions. Stroke 37:2940– 2945 Amtul Z, Nikolova S, Gao L, Keeley RJ, Bechberger JF, Fisher AL, Bartha R, Munoz DG, McDonald RJ, Naus CC, Wojtowicz JM, Hachinski V, Cechetto DF (2014) Comorbid Abeta toxicity and stroke: hippocampal atrophy, pathology, and cognitive deficit. Neurobiol Aging 35:1605–1614. doi:10.1016/j.neurobiolaging. 2014.01.005 Ballard C, O’Sullivan MJ (2013) Alzheimer disease and stroke: cognitive and neuroimaging predictors of AD and stroke. Nat Rev Neurol 9:605–606. doi:10.1038/nrneurol.2013.215 Breteler MM, Claus JJ, Grobbee DE, Hofman A (1994) Cardiovascular disease and distribution of cognitive function in elderly people: the Rotterdam Study. BMJ 308:1604–1608 Chi NF, Chien LN, Ku HL, Hu CJ, Chiou HY (2013) Alzheimer disease and risk of stroke: a population-based cohort study. Neurology 80:705–711 Deng J, Shen C, Wang YJ, Zhang M, Li J, Xu ZQ, Gao CY, Fang CQ, Zhou HD (2010) Nicotine exacerbates tau phosphorylation and cognitive impairment induced by amyloid-beta 25–35 in rats. Eur J Pharmacol 637:83–88. doi:10.1016/j.ejphar.2010.03.029 Fekih-Mrissa N, Klai S, Mrad M, Mansour M, Zaouali J, Gritli N, Mrissa R (2014) Apolipoprotein E genotypes associated with Alzheimer disease and concomitant stroke. J Stroke Cerebrovasc Dis 23:681–685. doi:10.1016/j.jstrokecerebrovasdis.2013.06.018 Fernandez-Lopez D, Faustino J, Daneman R, Zhou L, Lee SY, Derugin N, Wendland MF, Vexler ZS (2012) Blood-brain barrier permeability is increased after acute adult stroke but not neonatal stroke in the rat. J Neurosci 32:9588–9600. doi:10.1523/JNEUROSCI. 5977-11.2012 Garcia-Alloza M, Gregory J, Kuchibhotla KV, Fine S, Wei Y, Ayata C, Frosch MP, Greenberg SM, Bacskai BJ (2011) Cerebrovascular lesions induce transient beta-amyloid deposition. Brain 134:3697–3707. doi:10.1093/brain/awr300 Hardy J, Selkoe DJ (2002) The amyloid hypothesis of Alzheimer’s disease: progress and problems on the road to therapeutics. Science 297:353–356
Helzner EP, Luchsinger JA, Scarmeas N, Cosentino S, Brickman AM, Glymour MM, Stern Y (2009) Contribution of vascular risk factors to the progression in Alzheimer disease. Arch Neurol 66:343–348. doi:10.1001/archneur.66.3.343 Honig LS, Tang MX, Albert S, Costa R, Luchsinger J, Manly J, Stern Y, Mayeux R (2003) Stroke and the risk of Alzheimer disease. Arch Neurol 60:1707–1712 Imfeld P, Bodmer M, Schuerch M, Jick SS, Meier CR (2013) Risk of incident stroke in patients with Alzheimer disease or vascular dementia. Neurology 81:910–919. doi:10.1212/WNL. 0b013e3182a35151 Jendroska K, Poewe W, Daniel SE, Pluess J, Iwerssen-Schmidt H, Paulsen J, Barthel S, Schelosky L, Cervos-Navarro J, DeArmond SJ (1995) Ischemic stress induces deposition of amyloid beta immunoreactivity in human brain. Acta Neuropathol 90:461–466 Kim W, Hecht MH (2005) Sequence determinants of enhanced amyloidogenicity of Alzheimer A{beta}42 peptide relative to A{beta}40. J Biol Chem 280:35069–35076 Kruetzelmann A, Kohrmann M, Sobesky J, Cheng B, Rosenkranz M, Rother J, Schellinger PD, Ringleb P, Gerloff C, Fiehler J, Thomalla G (2011) Pretreatment diffusion-weighted imaging lesion volume predicts favorable outcome after intravenous thrombolysis with tissue-type plasminogen activator in acute ischemic stroke. Stroke 42:1251–1254. doi:10.1161/STRO KEAHA.110.600148 Lemere CA, Spooner ET, LaFrancois J, Malester B, Mori C, Leverone JF, Matsuoka Y, Taylor JW, DeMattos RB, Holtzman DM, Clements JD, Selkoe DJ, Duff KE (2003) Evidence for peripheral clearance of cerebral Abeta protein following chronic, active Abeta immunization in PSAPP mice. Neurobiol Dis 14:10–18 Li L, Zhang X, Yang D, Luo G, Chen S, Le W (2009) Hypoxia increases Abeta generation by altering beta- and gammacleavage of APP. Neurobiol Aging 30:1091–1098 Li J, Zhang M, Xu ZQ, Gao CY, Fang CQ, Deng J, Yan JC, Wang YJ, Zhou HD (2010) Vascular risk aggravates the progression of Alzheimer’s disease in a Chinese cohort. J Alzheimers Dis 20:491–500. doi:10.3233/JAD-2010-1383 Li J, Wang YJ, Zhang M, Xu ZQ, Gao CY, Fang CQ, Yan JC, Zhou HD, Chongqing Ageing Study, G (2011) Vascular risk factors promote conversion from mild cognitive impairment to Alzheimer disease. Neurology 76:1485–1491. doi:10.1212/WNL. 0b013e318217e7a4 Lorenz J, Kohlhoff H, Hansen HC, Kunze K, Bromm B (1998) Abetafiber mediated activation of cingulate cortex as correlate of central post-stroke pain. NeuroReport 9:659–663 Ly JV, Rowe CC, Villemagne VL, Zavala JA, Ma H, Sahathevan R, O’Keefe G, Gong SJ, Gunawan R, Churilov L, Saunder T, Ackerman U, Tochon-Danguy H, Donnan GA (2012) Subacute ischemic stroke is associated with focal 11C PiB positron emission tomography retention but not with global neocortical Abeta deposition. Stroke 43:1341–1346. doi:10.1161/STRO KEAHA.111.636266 Muresanu DF, Popa-Wagner A, Stan A, Buga AM, Popescu BO (2014) The vascular component of Alzheimer’s disease. Curr Neurovasc Res 11:168–176 Nakata-Kudo Y, Mizuno T, Yamada K, Shiga K, Yoshikawa K, Mori S, Nishimura T, Nakajima K, Nakagawa M (2006) Microbleeds in Alzheimer disease are more related to cerebral amyloid angiopathy than cerebrovascular disease. Dement Geriatr Cogn Disord 22:8–14 Nihashi T, Inao S, Kajita Y, Kawai T, Sugimoto T, Niwa M, Kabeya R, Hata N, Hayashi S, Yoshida J (2001) Expression and distribution of beta amyloid precursor protein and beta amyloid peptide in reactive astrocytes after transient middle cerebral artery occlusion. Acta Neurochir (Wien) 143:287–295
123
Neurotox Res Popa-Wagner A, Schroder E, Walker LC, Kessler C (1998) betaAmyloid precursor protein and ss-amyloid peptide immunoreactivity in the rat brain after middle cerebral artery occlusion: effect of age. Stroke 29:2196–2202 Popa-Wagner A, Buga AM, Popescu B, Muresanu D (2013) Vascular cognitive impairment, dementia, aging and energy demand. A vicious cycle. J Neural Transm. doi:10.1007/s00702-013-1129-3 Roberts KF, Elbert DL, Kasten TP, Patterson BW, Sigurdson WC, Connors RE, Ovod V, Munsell LY, Mawuenyega KG, MillerThomas MM, Moran CJ, Cross DT 3rd, Derdeyn CP, Bateman RJ (2014) Amyloid-beta efflux from the central nervous system into the plasma. Ann Neurol 76(6):837–844. doi:10.1002/ana. 24270 Takami K, Fujita-Hamabe W, Harada S, Tokuyama S (2011) Abeta and Adelta but not C-fibres are involved in stroke related pain and allodynia: an experimental study in mice. J Pharm Pharmacol 63:452–456. doi:10.1111/j.2042-7158.2010.01231.x Thiel A, Cechetto DF, Heiss WD, Hachinski V, Whitehead SN (2014) Amyloid burden, neuroinflammation, and links to cognitive decline after ischemic stroke. Stroke 45(9):2825–2829. doi:10. 1161/STROKEAHA.114.004285
123
van Dijk EJ, Prins ND, Vermeer SE, Hofman A, van Duijn CM, Koudstaal PJ, Breteler MM (2004) Plasma amyloid beta, apolipoprotein E, lacunar infarcts, and white matter lesions. Ann Neurol 55:570–575. doi:10.1002/ana.24270 van Duinen SG, Castano EM, Prelli F, Bots GT, Luyendijk W, Frangione B (1987) Hereditary cerebral hemorrhage with amyloidosis in patients of Dutch origin is related to Alzheimer disease. Proc Natl Acad Sci USA 84:5991–5994 Weller RO, Yow HY, Preston SD, Mazanti I, Nicoll JA (2002) Cerebrovascular disease is a major factor in the failure of elimination of Abeta from the aging human brain: implications for therapy of Alzheimer’s disease. Ann N Y Acad Sci 977:162–168 Wen Y, Onyewuchi O, Yang S, Liu R, Simpkins JW (2004) Increased beta-secretase activity and expression in rats following transient cerebral ischemia. Brain Res 1009:1–8 Zhang F, Eckman C, Younkin S, Hsiao KK, Iadecola C (1997) Increased susceptibility to ischemic brain damage in transgenic mice overexpressing the amyloid precursor protein. J Neurosci 17:7655–7661
ORIGINAL ARTICLE
Serum Ab is Predictive for Short-Term Neurological Deficits After Acute Ischemic Stroke Yu-Hui Liu • Hong-Yuan Cao • Ye-Ran Wang • Shu-Sheng Jiao • Xian-Le Bu • Fan Zeng • Qing-Hua Wang • Jing Li • Juan Deng • Hua-Dong Zhou • Yan-Jiang Wang
Received: 12 October 2014 / Revised: 29 December 2014 / Accepted: 12 January 2015 Ó Springer Science+Business Media New York 2015
Abstract Mounting evidence suggests that ischemic stroke (IS) is associated with Alzheimer’s disease (AD). IS and vascular risk factors increase the risk for AD. However, whether AD pathologies exist in IS and the effects of these pathologies on stroke remain unknown. In the present study, we aimed to investigate the alterations of serum Ab after acute IS (AIS), and its correlations with the neurological deficits, infarction volume, and site after stroke. AIS patients (n = 35) were recruited within 24 h of symptom onset. Age- and gender-matched AD patients (n = 48) and cognitively normal controls (NC, n = 37) were also enrolled. Serum Ab40 and Ab42 and the National Institute of Health Stroke Scale Score (NIHSS) were measured on day 1, 3, and 7 after stroke onset. We found that serum Ab40 and Ab42 levels were increased at day 1 and reached peak levels at day 3, and decreased to pre-stroke levels at day 7. Serum Ab40 levels at day 1 were correlated with the NIHSS scores and infarction volume of AIS patients. Serum Ab42 levels at day 1 were significantly higher in IS patients with dominant gray matter infarction. Serum Ab40 levels at day 1 were predictive for NIHSS at day 7. Our results indicate that AIS can induce the generation of Ab in the brain, which may in turn be involved in the pathogenesis of neurological deficits after
Yu-Hui Liu and Hong-Yuan Cao have contributed equally to this work. Y.-H. Liu H.-Y. Cao Y.-R. Wang S.-S. Jiao X.-L. Bu F. Zeng Q.-H. Wang J. Li J. Deng H.-D. Zhou Y.-J. Wang (&) Department of Neurology and Centre for Clinical Neuroscience, Daping Hospital and Institute of Field Surgery, Third Military Medical University, 10 Changjiang Branch Road, Yuzhong, Chongqing, China e-mail: [email protected]
stroke. Serum Ab might be predictive for the short-term neurological deficits after AIS. Keywords
Amyloid-beta Ischemic stroke Alzheimer
Introduction Ischemic stroke (IS) is an enormous threat to individual health as a leading cause of death and disability. The association between IS and Alzheimer disease (AD) has been previously reported (Honig et al. 2003; Imfeld et al. 2013). Epidemiological studies have revealed that vascular risk factors increase risk for AD, and cerebrovascular diseases increase the incidence and aggravate the clinical symptoms of AD (Breteler et al. 1994; Helzner et al. 2009). However, the pathophysiological mechanism underlying these associations remains unknown. Amyloid-beta peptide (Ab) is suggested to play a pivotal or causative role in the pathogenesis of AD. Overproduction or accumulation of Ab in the brain can cause secondary pathological events such as hyperphosphorylation of tau, neuroinflammation, oxidative stress, neurite degeneration, and neuronal death, which subsequently lead to dementia (Hardy and Selkoe 2002). The association between cerebral Ab and brain ischemia has been previously reported (Aho et al. 2006; Jendroska et al. 1995; Nihashi et al. 2001; PopaWagner et al. 1998). Previous studies have demonstrated that ischemic attack is associated with transient Ab accumulation in the brain of animals (Garcia-Alloza et al. 2011), and serum of after acute IS (AIS) patients (van Dijk et al. 2004). This might be resulted from increase in Ab generation via enhanced b- and c-cleavage of amyloid-beta peptide precursor (APP) (Li et al. 2009), or impaired cerebral Ab clearance after ischemic attack (Weller et al. 2002).
123
Neurotox Res
However, while we are thinking that IS contributes to the pathogenesis of AD, it remains unknown the impact of elevated Ab on the functional outcomes of AIS. As brain Ab equilibrates with serum Ab, serum Ab can reflect the levels of brain Ab (Roberts et al. 2014). In the present study, we investigated the alterations of serum Ab levels after AIS, and the correlations between serum Ab and the neurological deficits after stroke.
Subjects and Methods Subjects A total of 35 AIS patients, who were not suitable for thrombolysis due to their onset-to-door time was more than 4.5 h, were consecutively recruited from Daping Hospital during December 2013 to May 2014. Thirty seven age- and gender-matched cognitively normal controls (NC) were randomly recruited from health examination center of Daping hospital at the same time frame. Forty eight age- and gender-matched AD patients were randomly selected from bank of Chongqing Aging Study (Li et al. 2011). The subjects were not eligible if they: (1) had a history of dementia or mild cognitive impairment before stroke; (2) had severe cardiac, pulmonary, hepatic, renal diseases, or any kinds of tumors; (3) had chronic autoimmune or inflammatory diseases, or were on long-term use of nonsteroidal antiinflammatory drug; and (4) declined to participate the study. The study was approved by the Institutional Review Board of Daping Hospital, and registered in the Chinese Clinical Trial Registry (No. ChiCTR-OCC-12001966). Clinical Assessment and Treatment of AIS Patients The demographic data, medical history, and severity of neurological deficits were collected and assessed. All patients underwent computed tomography (CT) of the head at admission, and underwent angiography (CTA) and magnetic resonance imaging (MRI) of the head 24 h later after disease onset. Diagnosis of AIS was made based on the persistent symptom and signs of neurological deficits and acute ischemic lesions on brain imaging. Fasting blood was sampled for measuring hemogram, fasting glucose, thyroxin, creatinine, uric acid, transaminase, total cholesterol, Ab40, and Ab42. Blood was sampled between 07:00 and 09:00 a.m. in order to take into account a possible circadian rhythm; serum was separated within 30 min after sampling and stored at -80 °C until further analysis. For the recruited AIS patients, blood was sampled at the 1st, 3rd, and 7th day after stroke onset. Meanwhile, the severity of AIS was evaluated with the National Institutes of Health Stroke Scale (NIHSS, a 15-item validated neurological
123
examination scale with scores ranging from 0 to 42, with higher scores indicating greater deficits) at admission, day 3, and 7 after stroke onset. AIS patients were treated with standard medical care in a dedicated stroke unit. No AIS patients included in the study were treated with thrombolysis during their hospital stay. Magnetic Resonance Imaging (MRI) All MRI were performed on a 3.0 Tesla clinical whole-body scanner with echoplanar capabilities. The MRI protocol included a T1- and a T2-weighted sequences, a fluid-attenuated inversion recovery sequence and an axial diffusion weighted imaging (DWI) sequence as described previously (Kruetzelmann et al. 2011). DWI infarction volumes were calculated using locally established software. The infarction sites of each patient were evaluated by radiologists. Measurement of Serum Ab Serum Ab40 and Ab42 levels were measured using commercial ELISA kits (Betamark, Covance) according to the manufacturer’s instructions. Samples and standards were measured in duplicate, and the means of the duplicates were used for statistical analyses. Investigators were blinded for information of samples. Statistical Analysis All statistical analyses were performed with the software SPSS 18.0. The data were expressed as the mean ± SD, and significance was achieved when p \ 0.05. Continuous variables were tested for normal distribution with the Kolmogorov–Smirnov test. Differences in variables among groups were assessed using analysis of variance, Kruskal–Wallis tests, and Chi square tests, where appropriate. Paired samples t tests were used for the comparison of serum Ab levels at two different time points. The correlations between serum Ab levels and NIHSS scores of AIS patients were tested using Spearman correlation analysis. Linear regression models were used to test the role of serum Ab levels at the 1st day after the stroke onset in predicting the NIHSS scores at the 7th day when the discharge was planned for most of the patients.
Results Demographic Characteristics of Study Subjects The detailed demographic characteristics of subjects in the study are shown in Table 1. In the subjects of present study, there was no significant difference in characteristics of age, gender, education, frequencies of hypercholesterolemia, and
Neurotox Res Table 1 Demographic characteristics of study subjects NC (n = 37)
AD (n = 48)
Stroke (n = 35)
p
Female (%)
18 (48.65)
27 (56.25)
Agea
64.19 (42–71)
64.65 (49–77)
Educationb
9 (0–16)
9 (0–16)
Hyperlipidemia (%)
3 (8.11)
4 (8.33)
Hypertension (%)
10 (27.03)
10 (20.83)
19 (54.29)
0.004
DM (%)
3 (8.11)
8 (16.67)
6 (17.14)
0.445
Day 1: NIHSSc
NA
NA
7 (1–18)
NA
Day 3: NIHSSc
NA
NA
3 (0–13)
NA
Day 7: NIHSSc
NA
NA
2 (0–10)
NA
Infarction volume
NA
NA
Time intervaleIS
NA
NA
d
12 (34.29)
0.139
63.40 (42–89)
0.943
9 (0–16)
0.335
3 (8.57)
0.997
1.66 (0.10–102.35)
NA
9 (4–12)
NA
Time intervalIS between stroke onset and blood sampling NA not applicable, NIHSS National Institute of Health Stroke Scale Score a
Mean age in years (range)
b
Median education in years (range)
c
Median score (range)
d
Median volume in ml (range)
e
Median time intervalIS in hours (range)
diabetes mellitus (DM) among groups. AIS patients had higher frequencies of hypertension than AD patients and NC. Representative MRI images of all AIS patients are shown in Fig. 1.
Changes of Serum Ab Levels After Stroke Firstly, we compared serum Ab levels of the AIS patients with that of AD patients and NC. Serum Ab40 and Ab42 levels of AIS patients at day 1 (Ab40, p \ 0.001; Ab42, p = 0.014) and day 3 (Ab40, p \ 0.001; Ab42, p = 0.007) were significantly higher than that of NC. Notably, serum Ab40 (p = 0.032) and Ab42 (p = 0.034) levels of IS patients at day 3 were significantly higher than that of AD patients. Serum Ab40 (p = 0.366) and Ab42 (p = 0.204) of IS patients at day 7 decreased to pre-stroke levels. We next investigated the time course of changes in serum Ab levels after AIS. Interestingly, serum Ab40 reached a peak levels at day 3 (day 1 vs. 3, p = 0.039), and decreased to the levels which were comparable with that of NC at day 7 (day 3 vs. 7, p \ 0.001). However, there was no significant increase in serum Ab42 levels at day 3 relative to day 1 (p = 0.639). Similar to serum Ab40 levels, serum Ab42 levels decreased at day 7 (day 3 vs. 7, p = 0.018) (Fig. 2). Serum Ab40 (p = 0.372) and Ab42 (p = 0.204) levels of AIS patients at day 7 were comparable with that of NC. These data suggest that serum Ab levels increased at day 1 and 3, and decreased to normal levels at day 7 after onset of stroke.
Correlations Between Serum Ab Levels and NIHSS Scores After Stroke We then investigate the correlations between serum Ab levels and the severity of neurological deficits in AIS patients. Serum Ab40 levels at day 1 were correlated with the NIHSS scores at day 1. However, serum Ab40 levels at day 3 and 7 were not correlated with the NIHSS scores at the corresponding days. Meanwhile, serum Ab42 levels were not correlated with NIHSS scores at the corresponding days (Table 2). We further conducted linear regression analysis to investigate the role of serum Ab levels at day 1 for predicting NIHSS scores at day 7 when most of the AIS patients were planed for discharge, with NIHSS scores at day 7 as dependent variable and the contributing factors, including age, gender, education, hyperlipidemia, hypertension DM, and the time interval between stroke onset and blood sampling as independent variables. Interestingly, we found a significant predictive effect of serum Ab40, but not Ab42 levels, at day 1 for NIHSS scores at day 7 (Table 3). Correlations of Serum Ab Levels with Infarction Volume and Site of Stroke Spearman correlation analysis was conducted to investigate the correlations between serum Ab levels and lesion volumes of AIS patients. Interestingly, serum Ab40 levels at day 1 were correlated with infarction volume of AIS.
123
Neurotox Res
Fig. 1 Representative MRI images of all the AIS patients in the study. Infarction lesions are demonstrated as hyperintensive signals in DWI. The numbers at upper left of each image denote the patient number
However, no correlations were observed between serum Ab42 levels and infarction volume (Table 2). Then, we investigated the correlation between serum Ab levels and infarction sites. AIS patients were divided into gray matter dominant (GMD) group (n = 22) in which the infarction zone is mainly composed of gray matter and the white matter dominant (WMD) group (n = 13) in which the infarction zone is mainly composed of white matter. Serum Ab40 levels were not significantly different between the two groups. Serum Ab42 levels at day 1, but not day 3 and 7, were significantly higher in the GMD group in comparison with that in the WMD group (Fig. 3).
Discussion In the present study, we found that serum Ab40 and Ab42 levels were increased after AIS. Serum Ab40 and Ab42
123
reached peak levels at day 3, and returned to levels which were comparable with normal levels at day 7 after AIS onset. Serum Ab40 levels were correlated with the infarction volume, and serum Ab40 levels at day 1 were predictive for the NIHSS scores at day 7. Serum Ab42 levels at day 1 were significantly higher in AIS patients with GMD infarction relative to those with WMD infarction. As common morbidities and leading causes of death and disabilities among the elderly (Ballard and O’Sullivan 2013), AD and IS are mutual risk factors for each other (Chi et al. 2013; Honig et al. 2003) and share common risk factors such as age, smoking (Deng et al. 2010), and apolipoprotein E status (Fekih-Mrissa et al. 2014). Cognitive functions essentially depend on cerebrovascular health and cognitive decline frequently occurs after IS (Muresanu et al. 2014). In AD patients, dysfunction of cerebral autoregulation and structural deterioration in cerebral blood
Neurotox Res
Fig. 2 Serum Ab levels are increased and change over time in AIS patients. Serum a Ab40 and b Ab42 levels in normal NC, AD patients and AIS patients at day 1, day 3 and day 7, Asterisk compared with
Table 2 Correlations between serum Ab levels and NIHSS scores of AIS patients
Ab
Time
NC, hash compared with AD. Changes of serum c Ab40 and d Ab42 levels along with time. * and #p \ 0.05, ** and ##p \ 0.01
NIHSS
Infarction volume
Day 1 c Ab40
Ab42
Day 3 c
p
Day 7 c
p
c
p
p
Day 1
0.350
0.039
0.251
0.147
0.306
0.074
0.441
Day 3
-0.207
0.234
-0.285
0.097
-0.190
0.274
0.322
0.008 0.059
Day 7
-0.155
0.374
-0.169
0.332
0.000
0.996
-0.230
0.183
Day 1
-0.003
0.986
-0.024
0.889
-0.139
0.426
0.039
0.826
Day 3
-0.038
0.829
-0.099
0.573
-0.244
0.157
0.217
0.211
Day 7
0.259
0.132
0.111
0.526
0.137
0.433
0.173
0.321
Table 3 Predictive effects of serum Ab levels at day 1 for NIHSS scores at day 7 after onset of AIS using linear regression models Variable
Coefficient
SE
t
p
95 % confidence interval
Ab40
0.044
0.018
2.503
0.019
0.008–0.081
Ab42
-0.013
0.018
-0.696
0.493
-0.049–0.024
Adjusted for confounders, including age, gender, education, hyperlipidemia, hypertension, DM, and the time interval between stroke onset and blood sampling
123
Neurotox Res
Fig. 3 Comparison of serum Ab levels according to infarction site. *p \ 0.05, **p \ 0.01. GMD denotes gray matter dominant group and WMD denotes white matter dominant group
vessels impairs the cerebral blood flow and increases the neuronal degeneration and susceptibility to ischemia (Popa-Wagner et al. 2013). IS is revealed to increase the risk for AD, especially in cases with vascular risk factors such as hypertension, diabetes, or heart diseases (Honig et al. 2003). In our and others’ studies, vascular risk factors are suggested to promote AD incidence (Li et al. 2011) and progression (Helzner et al. 2009; Li et al. 2010). AD also increases the risk for cerebrovascular events, such as IS (Chi et al. 2013) and hemorrhage (van Duinen et al. 1987), which is likely due to Ab-directed vascular impairment (Nakata-Kudo et al. 2006). Previous animal studies suggest that ischemia lesions may lead to rapid deposition of Ab in the brain (GarciaAlloza et al. 2011). This was consistent with a previous human study which indicates that IS stress induces deposition of Ab immunoreactivity in the brain (Jendroska et al. 1995). It is further demonstrated that IS is associated with focal Ab deposition at the ischemic sites (Ly et al. 2012). The local ischemic effect on Ab accumulation in IS brain may be related to an upregulation and alteration of APP processing favoring amyloidogenic pathways, with increased b-secretase activity observed in rats after transient ischemic attack (Wen et al. 2004). Likewise, as ischemia is always accompanied with neuroinflammation, it is suggested that neuroinflammation also plays a role in promoting Ab generation and accumulation after stroke (Thiel et al. 2014). It is also possible that Ab clearance abilities were compromised after AIS (Garcia-Alloza et al. 2011). As there is equilibrium of Ab between the periphery and the brain, Ab might efflux from brain to periphery after ischemic insult (Lemere et al. 2003). Accordingly, levels of serum Ab can reflect the Ab levels in the brain. Human evidence regarding serum Ab levels after AIS is still lacking. In the present study, we found that AIS patients
123
had increase in both serum Ab40 and Ab42 levels, which are consistent with a previous study demonstrating increased peripheral Ab40 levels after AIS (van Dijk et al. 2004). The increase of Ab species in periphery might be subsequent to the increase of Ab in the brain after ischemic attack and its efflux into periphery. Another possibility is that brain ischemic insults may increase the permeability of the blood–brain barrier (Fernandez-Lopez et al. 2012). The two mechanisms may work synergistically. It is notable that serum Ab levels were increased at the first day after stroke onset, indicating that the increase of serum Ab might be an acute phase response to AIS. Interestingly, we further found peak levels of serum Ab at day 3 and normal levels at day 7, indicating that the increase of Ab after AIS is transient. This is consistent with previous animal studies (Garcia-Alloza et al. 2011), and can explain the paradox that there is no local increase in amyloid burden adjacent to cerebral infarcts in human brain (Garcia-Alloza et al. 2011). Although previous animal studies had revealed the Abinduced susceptibility to brain ischemia damage (Zhang et al. 1997), an important issue regarding whether the transient increase of Ab had an impact on neurological deficits after stroke still remains unclear. In animal models, Ab is suggested to be involved in stroke-related pain and allodynia (Lorenz et al. 1998; Takami et al. 2011) and cognitive impairment after stroke (Thiel et al. 2014). Brain injection of Ab results in hippocampal atrophy, AD-like pathologies, and cognitive deficit in animal models of stroke (Amtul et al. 2014). In the present study, we found that Ab levels were correlated with neurological deficits after AIS, suggesting that Ab is an important factor involved in the pathogenesis of stroke. Previous studies suggest that increase of Ab is confined focally around the ischemic site (Ly et al. 2012). This might explain the correlations between serum Ab40 levels at day 1 with infarction volume of AIS patients in the present study (Table 2). Moreover, we found that serum Ab42 levels at day 1 were significantly higher in the GMD group relative to WMD group. Serum Ab40 levels at day 1 and Ab42 levels at day 3 were slightly higher in the GMD group, although no statistical significance was reached. This finding suggests that neurons under ischemia might be more prone to generate Ab compared with ischemia of axons. Another important finding in the present study is that serum Ab40 levels at the onset day of AIS predict the NIHSS scores 1 week after, suggesting that Ab is involved in the pathogenesis of neurological deficits after AIS, and Ab might be a biomarker of severity of AIS. Compared with Ab40, Ab42 may be less prone to efflux from the brain to blood, as it has higher capacity of aggregation and is prone to deposit in the brain (Kim and Hecht 2005). Thus, serum Ab42 might be less sensitive to reflect brain
Neurotox Res
pathogenesis of ischemia than Ab40, as demonstrated in the present study. In summary, the present study is the first study to investigate the alterations of serum Ab levels in IS patients with the disease progression. Our findings suggest that AIS can induce transient generation of Ab in the brain, which might in turn be involved in the pathogenesis of neurological deficits after AIS. Serum Ab is predictive for the neurological deficits after stroke, suggesting that Ab is involved in the development of neurological deficits after stroke. The pathophysiological significance of the shortterm increase of serum Ab for long-term prognosis of the disease needs to be addressed in the future. Acknowledgments This work was supported by the National Natural Science Foundation of China (30973144), PLA Healthcare Research Grant (13BJZ31), Chinese Postdoctor Scientific Grant (2013T60955), and Chongqing Postdoctor Research Grant (XM201342). Conflict of interest
None.
References Aho L, Jolkkonen J, Alafuzoff I (2006) Beta-amyloid aggregation in human brains with cerebrovascular lesions. Stroke 37:2940– 2945 Amtul Z, Nikolova S, Gao L, Keeley RJ, Bechberger JF, Fisher AL, Bartha R, Munoz DG, McDonald RJ, Naus CC, Wojtowicz JM, Hachinski V, Cechetto DF (2014) Comorbid Abeta toxicity and stroke: hippocampal atrophy, pathology, and cognitive deficit. Neurobiol Aging 35:1605–1614. doi:10.1016/j.neurobiolaging. 2014.01.005 Ballard C, O’Sullivan MJ (2013) Alzheimer disease and stroke: cognitive and neuroimaging predictors of AD and stroke. Nat Rev Neurol 9:605–606. doi:10.1038/nrneurol.2013.215 Breteler MM, Claus JJ, Grobbee DE, Hofman A (1994) Cardiovascular disease and distribution of cognitive function in elderly people: the Rotterdam Study. BMJ 308:1604–1608 Chi NF, Chien LN, Ku HL, Hu CJ, Chiou HY (2013) Alzheimer disease and risk of stroke: a population-based cohort study. Neurology 80:705–711 Deng J, Shen C, Wang YJ, Zhang M, Li J, Xu ZQ, Gao CY, Fang CQ, Zhou HD (2010) Nicotine exacerbates tau phosphorylation and cognitive impairment induced by amyloid-beta 25–35 in rats. Eur J Pharmacol 637:83–88. doi:10.1016/j.ejphar.2010.03.029 Fekih-Mrissa N, Klai S, Mrad M, Mansour M, Zaouali J, Gritli N, Mrissa R (2014) Apolipoprotein E genotypes associated with Alzheimer disease and concomitant stroke. J Stroke Cerebrovasc Dis 23:681–685. doi:10.1016/j.jstrokecerebrovasdis.2013.06.018 Fernandez-Lopez D, Faustino J, Daneman R, Zhou L, Lee SY, Derugin N, Wendland MF, Vexler ZS (2012) Blood-brain barrier permeability is increased after acute adult stroke but not neonatal stroke in the rat. J Neurosci 32:9588–9600. doi:10.1523/JNEUROSCI. 5977-11.2012 Garcia-Alloza M, Gregory J, Kuchibhotla KV, Fine S, Wei Y, Ayata C, Frosch MP, Greenberg SM, Bacskai BJ (2011) Cerebrovascular lesions induce transient beta-amyloid deposition. Brain 134:3697–3707. doi:10.1093/brain/awr300 Hardy J, Selkoe DJ (2002) The amyloid hypothesis of Alzheimer’s disease: progress and problems on the road to therapeutics. Science 297:353–356
Helzner EP, Luchsinger JA, Scarmeas N, Cosentino S, Brickman AM, Glymour MM, Stern Y (2009) Contribution of vascular risk factors to the progression in Alzheimer disease. Arch Neurol 66:343–348. doi:10.1001/archneur.66.3.343 Honig LS, Tang MX, Albert S, Costa R, Luchsinger J, Manly J, Stern Y, Mayeux R (2003) Stroke and the risk of Alzheimer disease. Arch Neurol 60:1707–1712 Imfeld P, Bodmer M, Schuerch M, Jick SS, Meier CR (2013) Risk of incident stroke in patients with Alzheimer disease or vascular dementia. Neurology 81:910–919. doi:10.1212/WNL. 0b013e3182a35151 Jendroska K, Poewe W, Daniel SE, Pluess J, Iwerssen-Schmidt H, Paulsen J, Barthel S, Schelosky L, Cervos-Navarro J, DeArmond SJ (1995) Ischemic stress induces deposition of amyloid beta immunoreactivity in human brain. Acta Neuropathol 90:461–466 Kim W, Hecht MH (2005) Sequence determinants of enhanced amyloidogenicity of Alzheimer A{beta}42 peptide relative to A{beta}40. J Biol Chem 280:35069–35076 Kruetzelmann A, Kohrmann M, Sobesky J, Cheng B, Rosenkranz M, Rother J, Schellinger PD, Ringleb P, Gerloff C, Fiehler J, Thomalla G (2011) Pretreatment diffusion-weighted imaging lesion volume predicts favorable outcome after intravenous thrombolysis with tissue-type plasminogen activator in acute ischemic stroke. Stroke 42:1251–1254. doi:10.1161/STRO KEAHA.110.600148 Lemere CA, Spooner ET, LaFrancois J, Malester B, Mori C, Leverone JF, Matsuoka Y, Taylor JW, DeMattos RB, Holtzman DM, Clements JD, Selkoe DJ, Duff KE (2003) Evidence for peripheral clearance of cerebral Abeta protein following chronic, active Abeta immunization in PSAPP mice. Neurobiol Dis 14:10–18 Li L, Zhang X, Yang D, Luo G, Chen S, Le W (2009) Hypoxia increases Abeta generation by altering beta- and gammacleavage of APP. Neurobiol Aging 30:1091–1098 Li J, Zhang M, Xu ZQ, Gao CY, Fang CQ, Deng J, Yan JC, Wang YJ, Zhou HD (2010) Vascular risk aggravates the progression of Alzheimer’s disease in a Chinese cohort. J Alzheimers Dis 20:491–500. doi:10.3233/JAD-2010-1383 Li J, Wang YJ, Zhang M, Xu ZQ, Gao CY, Fang CQ, Yan JC, Zhou HD, Chongqing Ageing Study, G (2011) Vascular risk factors promote conversion from mild cognitive impairment to Alzheimer disease. Neurology 76:1485–1491. doi:10.1212/WNL. 0b013e318217e7a4 Lorenz J, Kohlhoff H, Hansen HC, Kunze K, Bromm B (1998) Abetafiber mediated activation of cingulate cortex as correlate of central post-stroke pain. NeuroReport 9:659–663 Ly JV, Rowe CC, Villemagne VL, Zavala JA, Ma H, Sahathevan R, O’Keefe G, Gong SJ, Gunawan R, Churilov L, Saunder T, Ackerman U, Tochon-Danguy H, Donnan GA (2012) Subacute ischemic stroke is associated with focal 11C PiB positron emission tomography retention but not with global neocortical Abeta deposition. Stroke 43:1341–1346. doi:10.1161/STRO KEAHA.111.636266 Muresanu DF, Popa-Wagner A, Stan A, Buga AM, Popescu BO (2014) The vascular component of Alzheimer’s disease. Curr Neurovasc Res 11:168–176 Nakata-Kudo Y, Mizuno T, Yamada K, Shiga K, Yoshikawa K, Mori S, Nishimura T, Nakajima K, Nakagawa M (2006) Microbleeds in Alzheimer disease are more related to cerebral amyloid angiopathy than cerebrovascular disease. Dement Geriatr Cogn Disord 22:8–14 Nihashi T, Inao S, Kajita Y, Kawai T, Sugimoto T, Niwa M, Kabeya R, Hata N, Hayashi S, Yoshida J (2001) Expression and distribution of beta amyloid precursor protein and beta amyloid peptide in reactive astrocytes after transient middle cerebral artery occlusion. Acta Neurochir (Wien) 143:287–295
123
Neurotox Res Popa-Wagner A, Schroder E, Walker LC, Kessler C (1998) betaAmyloid precursor protein and ss-amyloid peptide immunoreactivity in the rat brain after middle cerebral artery occlusion: effect of age. Stroke 29:2196–2202 Popa-Wagner A, Buga AM, Popescu B, Muresanu D (2013) Vascular cognitive impairment, dementia, aging and energy demand. A vicious cycle. J Neural Transm. doi:10.1007/s00702-013-1129-3 Roberts KF, Elbert DL, Kasten TP, Patterson BW, Sigurdson WC, Connors RE, Ovod V, Munsell LY, Mawuenyega KG, MillerThomas MM, Moran CJ, Cross DT 3rd, Derdeyn CP, Bateman RJ (2014) Amyloid-beta efflux from the central nervous system into the plasma. Ann Neurol 76(6):837–844. doi:10.1002/ana. 24270 Takami K, Fujita-Hamabe W, Harada S, Tokuyama S (2011) Abeta and Adelta but not C-fibres are involved in stroke related pain and allodynia: an experimental study in mice. J Pharm Pharmacol 63:452–456. doi:10.1111/j.2042-7158.2010.01231.x Thiel A, Cechetto DF, Heiss WD, Hachinski V, Whitehead SN (2014) Amyloid burden, neuroinflammation, and links to cognitive decline after ischemic stroke. Stroke 45(9):2825–2829. doi:10. 1161/STROKEAHA.114.004285
123
van Dijk EJ, Prins ND, Vermeer SE, Hofman A, van Duijn CM, Koudstaal PJ, Breteler MM (2004) Plasma amyloid beta, apolipoprotein E, lacunar infarcts, and white matter lesions. Ann Neurol 55:570–575. doi:10.1002/ana.24270 van Duinen SG, Castano EM, Prelli F, Bots GT, Luyendijk W, Frangione B (1987) Hereditary cerebral hemorrhage with amyloidosis in patients of Dutch origin is related to Alzheimer disease. Proc Natl Acad Sci USA 84:5991–5994 Weller RO, Yow HY, Preston SD, Mazanti I, Nicoll JA (2002) Cerebrovascular disease is a major factor in the failure of elimination of Abeta from the aging human brain: implications for therapy of Alzheimer’s disease. Ann N Y Acad Sci 977:162–168 Wen Y, Onyewuchi O, Yang S, Liu R, Simpkins JW (2004) Increased beta-secretase activity and expression in rats following transient cerebral ischemia. Brain Res 1009:1–8 Zhang F, Eckman C, Younkin S, Hsiao KK, Iadecola C (1997) Increased susceptibility to ischemic brain damage in transgenic mice overexpressing the amyloid precursor protein. J Neurosci 17:7655–7661
